Light emitting device and method of fabricating the same
By using carbon nanotubes and conductive materials to form a conductive interconnect layer in light-emitting diodes, and then removing the carbon nanotubes through a laser dissociation process, the problems of low luminous efficiency and unstable conductivity are solved, achieving efficient light transmission and good heat dissipation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHONGQING KONKA PHOTOELECTRIC TECH RES INST CO LTD
- Filing Date
- 2021-07-05
- Publication Date
- 2026-07-03
Smart Images
Figure CN115588680B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor light-emitting device technology, and in particular to a light-emitting device and its fabrication method. Background Technology
[0002] The luminous efficiency of current light-emitting diodes is relatively low because their light extraction efficiency is also low. The factors limiting the light extraction efficiency of light-emitting diodes are the absorption of light by the material and the blocking of light by the material.
[0003] To address these issues, existing technologies combine several light-emitting diodes (LEDs) into an array to increase luminous efficiency. However, the materials used for current spreading in this LED array are typically oxides (such as ITO, indium tin oxide). These oxides degrade upon exposure to high-energy light, affecting their conductivity. Additionally, metals are used for interconnection, but since metals are opaque, they block some light, further reducing the luminous efficiency of the LEDs.
[0004] Therefore, how to improve conductivity while increasing luminous efficiency and reducing light shading is an urgent problem to be solved. Summary of the Invention
[0005] In view of the shortcomings of the prior art, the purpose of this application is to provide a light-emitting device and a method for manufacturing the same, which aims to solve the problem of how to improve conductivity and reduce light occlusion while increasing luminous efficiency.
[0006] A method for manufacturing a light-emitting device, comprising:
[0007] An epitaxial structure is provided; wherein the epitaxial structure includes a substrate and a plurality of array structures disposed on the substrate;
[0008] An insulating layer is covered on each of the array structures;
[0009] A conductive interconnect layer is formed on the insulating layer; wherein the conductive interconnect layer includes carbon nanotubes and a conductive material filled inside the carbon nanotubes;
[0010] Electrodes are fabricated on the side of each array structure that faces away from the substrate;
[0011] The carbon nanotubes in the conductive interconnect layer are removed by a laser dissociation process.
[0012] By forming multiple array structures, luminescence efficiency can be improved. By forming a conductive interconnect layer on an insulating layer and then removing the carbon nanotubes from the conductive interconnect layer, a conductive material layer with a size of nanometer is formed. Compared with directly forming a nanometer-scale conductive layer, the cost of making a precision photomask is eliminated. The formed conductive material layer is less prone to deformation than traditional oxides. The nanometer-scale conductive material layer has better light transmittance than traditional metal patterns.
[0013] Optionally, forming a conductive interconnect layer on the insulating layer includes:
[0014] A substrate is provided having a conductive interconnect layer; wherein the conductive interconnect layer comprises carbon nanotubes and a conductive material filled inside the carbon nanotubes;
[0015] The side of the base carrier having the conductive interconnect layer is placed above the insulating layer;
[0016] Apply pressure continuously from the side of the base carrier away from the conductive interconnect layer until the conductive interconnect layer adheres to the insulating layer; then remove the base carrier.
[0017] or,
[0018] A dispersion containing a conductive interconnect layer is coated on the insulating layer; wherein the conductive interconnect layer comprises carbon nanotubes and a conductive material filled inside the carbon nanotubes;
[0019] The dispersion is removed to form the conductive interconnect layer.
[0020] Optional, also includes:
[0021] Remove the substrate;
[0022] The epitaxial structure, on the side opposite to the conductive interconnect layer, is bonded to a composite substrate; wherein the composite substrate comprises a silicon substrate and a carbon nanotube array formed on the silicon substrate. Due to the extremely high thermal conductivity of the carbon nanotubes in the composite substrate (up to 3500 W / mK at room temperature, and up to 6000 W / mK in extreme cases), this composite substrate serves as a heat dissipation surface, providing excellent heat dissipation and meeting heat dissipation requirements. Simultaneously, the silicon substrate in the composite substrate can be easily doped subsequently to form various driving circuits, saving process steps.
[0023] Optionally, the side of the epitaxial structure opposite to the conductive interconnect layer is bonded to the composite substrate through eutectic bonding and / or metallic bonding.
[0024] Optionally, the step of bonding the side of the epitaxial structure away from the conductive interconnect layer to the composite substrate via eutectic bonding includes:
[0025] A first adhesive layer is formed on the side of the epitaxial structure opposite to the conductive interconnect layer;
[0026] A second adhesive layer is formed on the side of the composite substrate having a carbon nanotube array;
[0027] The epitaxial structure is bonded to the composite substrate on the side opposite to the conductive interconnect layer through the first adhesive layer and the second adhesive layer.
[0028] Optionally, the epitaxial structure further includes a metal electrode layer disposed between the substrate and the array structure; the step of bonding the side of the epitaxial structure away from the conductive interconnect layer to the composite substrate by metal bonding includes:
[0029] A metal bonding layer is formed on the side of the composite substrate having a carbon nanotube array;
[0030] The metal electrode layer and the metal adhesive layer are bonded together by metal bonding.
[0031] Optionally, the removal of carbon nanotubes in the conductive interconnect layer by a laser dissociation process includes:
[0032] A laser with a first preset power is provided from one side of the conductive interconnect layer, the magnitude of which is sufficient to cause the carbon nanotubes in the conductive interconnect layer to be converted into carbon dioxide and overflow.
[0033] Optionally, the removal of carbon nanotubes in the conductive interconnect layer by a laser dissociation process includes:
[0034] A laser with a second preset power is provided from one side of the substrate. The magnitude of the second preset power is sufficient to peel off the substrate and, after attenuation by the array structure, cause the carbon nanotubes in the conductive interconnect layer to be converted into carbon dioxide and overflow.
[0035] Based on the same inventive concept, this application also provides a light-emitting device, comprising:
[0036] Epitaxial structure; the epitaxial structure includes a substrate and a plurality of array structures disposed on the substrate;
[0037] An insulating layer covering the plurality of array structures;
[0038] A conductive material layer, covering the insulating layer, is formed by removing the carbon nanotubes, which constitute a conductive interconnect layer consisting of carbon nanotubes and a conductive material filling the interior of the carbon nanotubes; and
[0039] Electrodes are formed on each of the array structures.
[0040] By forming multiple array structures, luminescence efficiency can be improved. By forming a conductive interconnect layer on an insulating layer and then removing the carbon nanotubes from the conductive interconnect layer, a conductive material layer with a size of nanometer is formed. Compared with directly forming a nanometer-scale conductive layer, the cost of making a precision photomask is eliminated. The formed conductive material layer is less prone to deformation than traditional oxides. The nanometer-scale conductive material layer has better light transmittance than traditional metal patterns.
[0041] Optionally, the conductive material layer includes multiple metal wires, which are arranged in any one or more ways, such as being parallel to each other, overlapping each other, or neither overlapping nor parallel.
[0042] Optionally, the conductive material layer may be made of any one of gold, silver, alkali metals, or alkaline earth metals.
[0043] Optionally, the light-emitting device further includes a composite substrate, the composite substrate comprising a silicon substrate and a carbon nanotube array formed on the silicon substrate, wherein the side of the array structure facing away from the conductive material layer is bonded to the composite substrate.
[0044] Optionally, the side of the array structure facing away from the conductive material layer is bonded to the composite substrate through eutectic bonding and / or metallic bonding.
[0045] Optionally, a first adhesive layer is formed on the side of the array structure away from the conductive material layer, and a second adhesive layer is formed on the side of the composite substrate having the carbon nanotube array. The first adhesive layer and the second adhesive layer are bonded by eutectic bonding.
[0046] Optionally, a metal electrode layer is formed on the side of the array structure opposite to the conductive material layer, and a metal bonding layer is formed on the side of the composite substrate having the carbon nanotube array. The metal electrode layer and the metal bonding layer are bonded by metal bonding.
[0047] Optionally, the light-emitting device further includes a buffer layer formed between the array structure on the side opposite to the conductive material layer and the composite substrate.
[0048] Optionally, the wavelength of the light emitted by the light-emitting device is between 320nm and 400nm; and / or between 280nm and 320nm; and / or between 200nm and 280nm. Attached Figure Description
[0049] Figure 1 This is a flowchart illustrating a method for fabricating a light-emitting device according to one embodiment.
[0050] Figure 2This is a schematic diagram of one step in a method for fabricating a light-emitting device according to one embodiment.
[0051] Figure 3 This is a schematic diagram of one step in a method for fabricating a light-emitting device according to one embodiment.
[0052] Figure 4 This is a schematic diagram of one step in a method for fabricating a light-emitting device according to one embodiment.
[0053] Figure 5 This is a schematic diagram of one step in a method for fabricating a light-emitting device according to one embodiment.
[0054] Figure 6 This is a schematic diagram of one step in a method for fabricating a light-emitting device according to one embodiment.
[0055] Figure 7 This is a schematic diagram of one step in a method for fabricating a light-emitting device according to one embodiment.
[0056] Figure 8 This is a schematic diagram of one step in a method for fabricating a light-emitting device according to one embodiment.
[0057] Figure 9 This is a schematic diagram of one step in a method for fabricating a light-emitting device according to one embodiment.
[0058] Figure 10 This is a schematic diagram of one step in a method for fabricating a light-emitting device according to one embodiment.
[0059] Figure 11 This is a schematic diagram of one step in a method for fabricating a light-emitting device according to one embodiment.
[0060] Figure 12 This is a schematic diagram of one step in a method for fabricating a light-emitting device according to one embodiment.
[0061] Figure 13 This is a schematic diagram of one step in a method for fabricating a light-emitting device according to one embodiment.
[0062] Explanation of reference numerals in the attached figures:
[0063] 10 - Substrate, 15 - Composite substrate;
[0064] 20-Stacked structure, 21-First semiconductor layer, 211-First sublayer, 22-Active layer, 221-Active sublayer, 23-Second semiconductor layer, 231-Second sublayer, 25-Array structure;
[0065] 30 - Insulation layer, 35 - Via;
[0066] 40 - Conductive interconnect layer, 45 - Conductive material layer;
[0067] 50-electrode;
[0068] 60 - Mask, 61 - Transparent area, 62 - Opaque area;
[0069] 71 - First laser, 72 - Second laser. Detailed Implementation
[0070] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.
[0071] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.
[0072] The luminous efficiency of current light-emitting diodes is relatively low because their light extraction efficiency is also low. The factors limiting the light extraction efficiency of light-emitting diodes are the absorption of light by the material and the blocking of light by the material.
[0073] To address these issues, existing technologies combine several light-emitting diodes (LEDs) into an array to increase luminous efficiency. However, the materials used for current spreading in this LED array are typically oxides (such as ITO, indium tin oxide). These oxides degrade upon exposure to high-energy light, affecting their conductivity. Additionally, metals are used for interconnection, but since metals are opaque, they block some light, further reducing the luminous efficiency of the LEDs.
[0074] Therefore, how to improve conductivity while increasing luminous efficiency and reducing light shading is an urgent problem to be solved.
[0075] Therefore, this application aims to provide a solution that can solve the above-mentioned technical problems, the details of which will be described in subsequent embodiments.
[0076] Please refer to Figure 1 This application provides a method for manufacturing a light-emitting device, including steps S10-S50, which are described in detail below.
[0077] Please refer to Figures 1 to 3Step S10: Provide an epitaxial structure; wherein the epitaxial structure includes a substrate 10 and a plurality of array structures 25 disposed on the substrate 10.
[0078] The specific steps of step S10 may include: fabricating a stacked structure 20, the stacked structure 20 including a first semiconductor layer 21, an active layer 22 and a second semiconductor layer 23 stacked together, and the stacked structure 20 being patterned to form multiple array structures 25.
[0079] For details, please refer to Figure 2 The substrate can be substrate 10, on which a first semiconductor layer 21, an active layer 22, and a second semiconductor layer 23 can be grown sequentially. Optionally, a buffer layer (not shown in the figure) can be grown on substrate 10 first, and then the first semiconductor layer 21, the active layer 22, and the second semiconductor layer 23 can be grown sequentially.
[0080] Alternatively, the substrate can be other types of substrates, and the laminate structure 20 is not grown on the substrate, but is connected to the substrate in subsequent processes by means such as bonding.
[0081] The substrate 10 can be made of sapphire, silicon (Si), silicon carbide (SiC), aluminum nitride (AlN), gallium nitride (GaN), etc., with sapphire being the preferred material. The substrate 10 serves as the basis for the subsequent growth of various structures.
[0082] The buffer layer can be made of aluminum nitride (AlN), gallium nitride (GaN), etc. The buffer layer is used to release the stress of the active layer 22 grown on the substrate 10 and improve the crystal quality of the active layer 22.
[0083] The first semiconductor layer 21 is made of N-type nitride, preferably aluminum gallium nitride (AlGaN).
[0084] The active layer 22 is a multiple quantum well (MQW) active layer. The active layer 22 is the light-emitting layer that emits light after carrier recombination, and it determines the emission wavelength. Optionally, the light-emitting device of this application emits ultraviolet (UV) light, specifically any one or more of the following: short-wave ultraviolet light (UVC) with a wavelength between 200nm and 280nm, medium-wave ultraviolet light (UVB) with a wavelength between 280nm and 320nm, and long-wave ultraviolet light (UVA) with a wavelength between 320nm and 400nm.
[0085] The second semiconductor layer 23 is made of P-type nitride, preferably P-type aluminum gallium nitride (AlGaN).
[0086] Please refer to Figure 2 and Figure 3The patterned stacked structure 20 forms multiple array structures 25. The patterning method can be photolithography, specifically by digging multiple trenches at intervals on the stacked structure 20. The trenches penetrate the second semiconductor layer 23 and the active layer 22, and extend into the first semiconductor layer 21 but do not penetrate it. The multiple array structures 25 are composed of the remaining parts after the original stacked structure 20 is patterned. Specifically, the array structure 25 includes the remaining first sub-layer 211 of the first semiconductor layer 21, the remaining active sub-layer 221 of the active layer 22, and the remaining second sub-layer 231 of the second semiconductor layer 23. The first sub-layer 211 further includes a common portion on the substrate 10 that is not penetrated by the trenches and an independent portion that is penetrated by the trenches. That is, the multiple array structures 25 are interconnected at the common portion of the first semiconductor layer 21, and the independent portions of the first semiconductor layer 21 and the active sub-layers 221 and 231 stacked on top of it are spaced apart.
[0087] Please refer to Figure 1 , Figure 3 and Figure 4 Step S20: Cover each array structure 25 with an insulating layer 30.
[0088] For details, please refer to Figure 4 After forming multiple array structures 25, an insulating layer 30 is applied, covering the array structures 25 and conforming to the sidewalls and bottom wall of the trench. The insulating layer 30 can be made of oxide, preferably silicon dioxide (SiO2). The process for forming the insulating layer 30 can be deposition, specifically chemical vapor deposition, physical vapor deposition, etc. The insulating layer 30 is used to prevent short circuits between the first semiconductor layer 21 and the second semiconductor layer 23 in each array structure 25.
[0089] Please refer to Figure 1 , Figure 4 and Figure 5 Step S20: A conductive interconnect layer 40 is formed on the insulating layer 30. The conductive interconnect layer 40 includes carbon nanotubes (CNTs) and a conductive material filled inside the carbon nanotubes.
[0090] Specifically, carbon nanotubes include, but are not limited to, single-walled, double-walled, or multi-walled carbon nanotube materials. The carbon nanotubes in this embodiment are metallic carbon nanotubes, satisfying: nm = 3k (k is an integer), where (n, m) represents the chirality index of the carbon nanotube material, which is directly related to the helicity and electrical properties of the carbon nanotube material.
[0091] The conductive material can be a nanomaterial, which is a metal or composite material with excellent electrical and thermal conductivity. Examples include gold, silver, alkali metals, or alkaline earth metals, with silver being the preferred material.
[0092] Specific methods for filling carbon nanotubes with conductive materials include arc discharge, molten salt electrolysis, template-assisted method, pyrolysis of organometallic compounds, capillary filling, solution chemistry, etc. For details, please refer to existing technologies, which will not be elaborated here.
[0093] The conductive interconnect layer 40 can be formed on the insulating layer 30 using any feasible method. Two embodiments are provided below.
[0094] In one embodiment, the method for forming the conductive interconnect layer 40 on the insulating layer 30 is a spin coating method, which includes: coating the insulating layer 30 with a dispersion containing the conductive interconnect layer 40 (not shown in the figure), and then removing the dispersion to form the conductive interconnect layer 40.
[0095] Specifically, firstly, carbon nanotubes filled with conductive nanomaterials are dispersed in a dispersion solution. Then, the dispersion solution is coated onto the insulating layer 30, and after removing the dispersion solution, a conductive interconnect layer 40 is formed. This method can relatively easily obtain a conductive interconnect layer 40 with a roughly uniform thickness, and the process is relatively simple.
[0096] In another embodiment, a base carrier having a conductive interconnect layer 40 is provided; wherein the conductive interconnect layer comprises carbon nanotubes and a conductive material filled inside the carbon nanotubes. The side of the base carrier having the conductive interconnect layer is placed over the insulating layer 30. Pressure is continuously applied from the side of the base carrier away from the conductive interconnect layer 50 until the conductive interconnect layer adheres to the insulating layer. The base carrier is then removed.
[0097] As a specific embodiment, the method for forming the conductive interconnect layer 40 on the insulating layer 30 can also be a spin coating method. Specifically, firstly, carbon nanotubes filled with nano-conductive materials are dispersed in a dispersion liquid, and then the dispersion liquid is spin-coated onto a flexible substrate (the flexible substrate is the base carrier); the dispersion liquid is removed to obtain the conductive interconnect layer 40 formed on the flexible substrate; the conductive interconnect layer 40 is bonded to the insulating layer 30, and the bonding can be achieved by methods such as vacuum adsorption or applying a certain force to one side of the flexible substrate; the flexible substrate is then removed.
[0098] In another specific embodiment, a conductive interconnect layer 40 is formed on the insulating layer 30 via a transfer structure. Specifically, the transfer structure includes a rigid substrate and a deformable adhesive layer (material may be polydimethylsiloxane, PDMS), a sacrificial layer, and the conductive interconnect layer 40, which are sequentially stacked on the rigid substrate. After the conductive interconnect layer 40 is brought into contact with the insulating layer 30, pressure is applied to one side of the rigid substrate to bond the conductive interconnect layer 40 to the insulating layer 30. Since both the sacrificial layer and the deformable adhesive layer have a certain degree of ductility, the conductive interconnect layer 40 is ensured to adhere tightly to the insulating layer 30. Then, the conductive interconnect layer 40 is separated from the transfer structure and formed on the insulating layer 30 by removing the sacrificial layer.
[0099] Please refer to Figure 1 , Figure 5 and Figure 6 Step S30: Electrode 50 is fabricated on the side of each array structure 25 away from the substrate 10.
[0100] Specifically, vias 35 can be formed in the conductive interconnect layer 40 and the insulating layer 30 on each array structure 25 to expose the second semiconductor layer 23 through the vias 35. The vias 35 can be formed by photolithography. The vias 35 enable electrical connection with the second semiconductor layer 23 to conduct current and thus achieve the light-emitting function.
[0101] Please refer to Figure 6 and Figure 7 An electrode 50 is formed on the second semiconductor layer 23 through a via 35.
[0102] Electrode 50 can be formed using a deposition process. The material of electrode 50 can be a pure metal, alloy, or non-metallic conductive material. Electrode 50 is connected to the bottom and sidewalls of via 35, i.e., electrode 50 is connected to the second semiconductor layer 23. Simultaneously, electrode 50 is connected to the insulating layer 30 and the conductive interconnect layer 40. In this embodiment, electrode 50 can be a P-electrode or an N-electrode. The P-electrode and N-electrode are used to connect to the driving circuit of the circuit backplane (not shown in the figure). The driving signal of the driving circuit is transmitted to each array structure 25 through the P-electrode and N-electrode, causing each array structure 25 to emit light. Each array structure 25 constitutes a light-emitting unit.
[0103] The conductive interconnect layer 40 forms an interconnect pattern connecting the various array structures 25. This interconnect pattern includes multiple composite wires, which can be arranged in one or more ways: parallel, overlapping, or neither overlapping nor parallel. Because the nano-conductive material is filled within carbon nanotubes, the unique structure of the carbon nanotubes allows the formed composite wires to be nanoscale in size. Compared to the traditional method of directly fabricating nanoscale metal wires using precision masks, this eliminates the cost of fabricating precision masks.
[0104] Please refer to Figure 1 , Figure 7 and Figure 13 Step S50: Remove carbon nanotubes in the conductive interconnect layer 40 by a laser dissociation process.
[0105] The carbon nanotubes in the conductive interconnect layer 40 are removed, so that the conductive interconnect layer 40 is entirely composed of conductive material, thus forming the conductive material layer 45.
[0106] The method for removing carbon nanotubes from the conductive interconnect layer 40 is a laser dissociation method, that is, using a laser to irradiate the conductive interconnect layer 40, causing the carbon nanotubes in the conductive interconnect layer 40 to be converted into carbon dioxide and released. The method of laser dissociation is also described in subsequent embodiments of this application, and will not be limited here.
[0107] Because the nano-conductive material is filled in the carbon nanotubes, when the carbon nanotubes are removed, the shape and structure of the remaining nano-conductive material forming the conductive material layer 45 remain largely unchanged from the shape and structure of the conductive interconnect layer 40. That is, the conductive material layer 45 includes multiple metal wires, which can be arranged in any one or more ways, such as parallel to each other, overlapping each other, or neither overlapping nor parallel. The dimensions of the multiple metal wires are on the nanometer scale.
[0108] The conductive material layer 45 serves as a current spreader. This layer is made of metal and will not deform under high-energy light, such as ultraviolet light, exhibiting better conductivity than metal oxides (such as indium tin oxide, IPO). Furthermore, the multiple metal wires in the conductive material layer 45 are nanometer-sized, providing better light transmittance than conventional metal patterns.
[0109] This embodiment improves luminous efficiency by forming multiple array structures 25. By forming a conductive interconnect layer 40 on the insulating layer 30 and then removing the carbon nanotubes in the conductive interconnect layer 40, a conductive material layer 45 with a size of nanometers is formed. Compared with directly forming a nanometer-sized conductive layer, the cost of making a precision photomask is saved. The formed conductive material layer is less prone to deformation than traditional oxides. The nanometer-sized conductive material layer has better light transmittance than traditional metal patterns.
[0110] Furthermore, if the carbon nanotubes in the conductive interconnect layer 40 are not removed, they will become brittle after being irradiated with high-energy ultraviolet light. To avoid this problem, an additional protective layer is required. However, if the carbon nanotubes in the conductive interconnect layer 40 are removed, the resulting conductive material layer 45 will contain almost no carbon nanotubes, thus eliminating the brittleness problem and the need for a protective layer.
[0111] Optional, please refer to Figure 7 and Figure 8 The fabrication method of this application further includes: removing the substrate 10 and bonding the epitaxial structure (i.e., multiple array structures 25) to a composite substrate 15 on the side away from the conductive interconnect layer 40; wherein the composite substrate 15 includes a silicon substrate and a carbon nanotube array formed on the silicon substrate.
[0112] Specifically, after forming electrode 50, substrate 10 can be replaced with composite substrate 15.
[0113] Light-emitting devices generate a lot of heat when emitting light, so heat dissipation needs to be considered. When the substrate 10 is used as the outer surface for heat dissipation, the heat dissipation effect is limited due to the material limitations of the substrate 10, making it difficult to meet the heat dissipation requirements.
[0114] Replacing substrate 10 with composite substrate 15 provides excellent heat dissipation as the outer surface for heat dissipation, as the carbon nanotubes in composite substrate 15 have very high thermal conductivity (up to 3500 W / mK at room temperature, and up to 6000 W / mK in extreme cases). This composite substrate 15 also facilitates subsequent doping to form various driving circuits, saving process steps.
[0115] Since the stacked structure 20 and the subsequent array structures 25 need to be grown on the substrate 10, the substrate 10 needs to be replaced with a composite substrate 15, and it is difficult to directly use the composite substrate 15 to grow the stacked structure 20 and the subsequent array structures 25.
[0116] The composite substrate 15 can be fabricated by forming a carbon nanotube array on a silicon substrate through methods such as spray pyrolysis, thermochemical vapor deposition, and spin coating. Taking spin coating as an example, the prepared metallic carbon nanotube material can be dispersed in a dispersion liquid, the dispersion liquid can be spin-coated onto the silicon substrate, and finally the dispersion liquid can be removed to obtain a silicon substrate with a carbon nanotube array, i.e., composite substrate 15.
[0117] Carbon nanotube arrays can be formed on the surface or inside the silicon substrate. Optionally, the carbon nanotube array is formed on one side surface of the silicon substrate. Preferably, the carbon nanotube array is formed on the side surface of the silicon substrate facing the first semiconductor layer 21, so that heat can be transferred to the carbon nanotube array with the shortest path and heat can be released as quickly as possible to achieve heat dissipation.
[0118] In one embodiment, please refer to Figure 7 and Figure 8The method of replacing substrate 10 with composite substrate 15 includes: peeling substrate 10; forming a first adhesive layer (not shown in the figure) on the side of the first semiconductor layer 21 facing away from the active layer 22, and forming a second adhesive layer (not shown in the figure) on the side of composite substrate 15 having carbon nanotube array; bonding the epitaxial structure (i.e., multiple array structures 25) to the side of composite substrate 15 facing away from conductive interconnect layer 40 by eutectic bonding through the first adhesive layer and the second adhesive layer.
[0119] Specifically, the method for peeling off the substrate 10 can be laser peeling. The principle is that the laser causes the material between the substrate 10 and the epitaxial structure (i.e., the multiple array structures 25), that is, the material between the substrate 10 and the first semiconductor layer 21, such as gallium nitride (GaN), to decompose into metallic gallium and nitrogen gas, thereby achieving peeling. The materials of the first adhesive layer and the second adhesive layer can be gold-tin alloy (AuSn). Gold-tin alloy, as a solder, has a good adhesion effect.
[0120] In another embodiment, please refer to 7 and Figure 8 Replacing substrate 10 with composite substrate 15 includes:
[0121] Please refer to Figure 2 A metal electrode layer (not shown) is formed on the substrate 10. A stacked structure 20 is formed on the metal electrode layer, and subsequently, multiple array structures 25 are formed between the metal layer and the substrate. Please refer to [reference needed]. Figure 7 and Figure 8 After the substrate 10 is peeled off, the metal electrode layer is located on the side of the first semiconductor layer 21 facing away from the active layer 22. The method for peeling off the substrate 10 can be laser peeling. A metal bonding layer is formed on the composite substrate 15. Preferably, the metal bonding layer is formed on the side of the composite substrate 15 with the carbon nanotube array. The metal electrode layer and the metal bonding layer are bonded by metal bonding.
[0122] For details, please refer to Figure 2 First, a metal electrode layer is formed on the substrate 10. Then, a subsequent stacked structure 20, namely a first semiconductor layer 21, an active layer 22, and a second semiconductor layer 23, is formed on the metal electrode layer. Optionally, a buffer layer can be formed on the metal electrode layer, and then the stacked structure 20 can be formed on the buffer layer. Please refer to [further details]. Figures 3 to 8 and Figure 13 Continue with the subsequent steps. After forming electrode 50, peel off substrate 10, separate metal electrode layer from substrate 10, and attach metal electrode layer to first semiconductor layer 21 (if no buffer layer) or buffer layer (if buffer layer).
[0123] The metal electrode layer can be multilayered. Specifically, it can be a P-type electrode layer, with the multilayers made of titanium (Ti), aluminum (Al), titanium (Ti), and gold (Au). Alternatively, it can be an N-type electrode layer, with the multilayers made of nickel (Ni) and copper (Au). The metal bonding layer can be made of gold (Au). The bonding between the metal electrode layer and the metal bonding layer achieves substrate bonding and electrical conductivity.
[0124] Please refer to Figures 8 to 11 and Figure 13 The carbon nanotubes in the conductive interconnect layer 40 are removed by a laser dissociation process, which includes: providing a first laser 71 from one side of the conductive interconnect layer 40, that is, the side of the second semiconductor layer 23 facing away from the active layer 22. The first laser 71 is a laser with a first preset power, the magnitude of which is sufficient to convert the carbon nanotubes in the conductive interconnect layer 40 into carbon dioxide and cause them to overflow.
[0125] Optionally, a mask 60 can be provided, which has a light-transmitting area 61 and an opaque area 62. The light-transmitting area 61 corresponds to the conductive interconnect layer 40, and the opaque area 62 corresponds to the electrode 50. A first laser 71 is used to irradiate the mask 60, and the first laser 71 shines on the conductive interconnect layer 40 through the light-transmitting area 61. The purpose of providing the mask 60 is to prevent the first laser 71 from affecting the adhesion of the electrode 50.
[0126] Specifically, the transmittance of the light-transmitting area 61 can be 0-100%, and a specific transmittance can be set as needed to achieve a fully transparent or semi-transparent effect. The specific positions of the light-transmitting area 61 and the opaque area 62 on the photomask 60 depend on the structure of the light-emitting device, such as... Figure 10 and Figure 11 Two embodiments of the mask 60 are shown. Figure 10 In the middle, the light-transmitting area 61 includes a portion extending along the row direction in a multi-row, multi-column arrangement, and a portion extending along the column direction in a multi-row, multi-column arrangement on the far left. Figure 11 In the photomask 60, the light-transmitting area 61 includes portions extending along the row direction in a multi-row, multi-column arrangement, and portions extending along the column direction in a single column and multiple rows on the far left and far right. The leftmost and rightmost light-transmitting areas 61 are staggered. All other areas outside the light-transmitting areas 61 are non-light-transmitting areas 61. It should be understood that the structure of the photomask 60 is not limited to... Figure 10 and Figure 11 As shown, there are other feasible solutions as well.
[0127] The radiation intensity (i.e., the first preset power) of the first laser 71 is 0.15~10W / cm2. This relatively low radiation intensity is sufficient to convert the carbon nanotubes in the conductive interconnect layer 40 into carbon dioxide. Because the radiation intensity of the first laser 71 is low, the impact on the adhesion of the electrode 50 is minimal even without a mask 60. However, high-precision masks 60 are expensive; therefore, to reduce costs, a solution without a mask 60 can be chosen. In high-level light-emitting devices, a mask 60 is required to achieve the best fabrication results.
[0128] Optionally, the first laser 71 can irradiate the entire conductive interconnect layer 40 to remove all carbon nanotubes in the conductive interconnect layer 40; alternatively, the first laser 71 can also irradiate only the interconnect pattern portion of the conductive interconnect layer 40, without irradiating other portions, to remove carbon nanotubes in the interconnect pattern portion of the conductive interconnect layer 40, while carbon nanotubes in other portions may not be removed.
[0129] By using a first laser 71 to irradiate the conductive interconnect layer 40, the carbon nanotubes in the conductive interconnect layer 40 are converted into carbon dioxide and overflow, thus achieving the removal of carbon nanotubes. The process is simple.
[0130] It should be noted that if a photomask is used directly to create nanoscale interconnect patterns (i.e., multiple metal wires), the size of the light-transmitting area 61 of the photomask needs to be at the nanoscale precision. However, in this embodiment, since the conductive interconnect layer 40 is a carbon nanotube filled with conductive material, the size of the interconnect pattern it forms is already at the nanoscale precision. Therefore, the precision requirement for the size of the light-transmitting area 61 of the photomask 60 is greatly reduced, thus reducing the cost of the photomask 60.
[0131] In one embodiment, please refer to Figure 12 and Figure 13 Removing carbon nanotubes from the conductive interconnect layer 40 includes:
[0132] A second laser 72 is provided from one side of the substrate 10. The second laser 72 has a second preset power, the magnitude of which is sufficient to peel off the substrate 10. After being attenuated by the array structure 25, the carbon nanotubes in the conductive interconnect layer 40 are converted into carbon dioxide and overflow.
[0133] Specifically, since the substrate 10 is typically removed using a laser lift-off process, a second laser 72 can be used to simultaneously remove the carbon nanotubes from both the glass and the conductive interconnect layer 40 of the substrate 10. After undergoing processes such as... Figures 2 to 7 After the steps shown, it is not necessary to use the following: Figures 7 to 9 Instead of the process shown, which involves first peeling off the substrate 10 and then removing the carbon nanotubes from the conductive interconnect layer 40, a method is employed as follows: Figure 7 , Figure 12 and Figure 13The process involves simultaneously stripping carbon nanotubes from the substrate 10 and the conductive interconnect layer 40.
[0134] The radiation intensity (i.e., the second preset power) of the second laser 72 is 4000-5000 W / cm2. On the one hand, the second laser 72 can peel off the substrate 10. On the other hand, the radiation intensity of the second laser 72 is attenuated after passing through the substrate 10, the buffer layer (if present), the first semiconductor layer 21, the active layer 22 and the second semiconductor layer 23. Since the carbon nanotubes in the conductive interconnect layer 40 only require a laser with a radiation intensity of 0.15-10 W / cm2 to be converted into carbon dioxide, the remaining energy after the second laser 72 is attenuated is still sufficient to convert the carbon nanotubes in the conductive interconnect layer 40 into carbon dioxide.
[0135] In this embodiment, the second laser 72 irradiates the entire substrate 10 and can penetrate the middle structure to irradiate all the conductive interconnect layers 40.
[0136] After peeling off the substrate 10 and removing the carbon nanotubes in the conductive interconnect layer 40, the composite substrate 15 can be bonded. The above-described embodiments are sufficient for reference and will not be repeated here.
[0137] Please refer to Figure 13 Based on the same inventive concept as in the foregoing embodiments, this application also provides a light-emitting device, including:
[0138] Multiple array structures 25, each array structure 25 including a stacked first semiconductor layer 21, an active layer 22 and a second semiconductor layer 23;
[0139] An insulating layer 30 covers multiple array structures 25;
[0140] A conductive material layer 45 covers the insulating layer 30. The conductive material layer 45 is formed by removing the carbon nanotubes from the conductive interconnect layer 40, which consists of carbon nanotubes and conductive material filled inside the carbon nanotubes.
[0141] Electrodes 50 are formed on each array structure 25. Specifically, a via 35 is formed in the conductive interconnect layer 40 and the insulating layer 30 of each array structure 25, through which the second semiconductor layer 23 is exposed, and an electrode 50 is formed on the second semiconductor layer 23 of each array structure 25 through the via 35.
[0142] The structure, materials, and manufacturing processes of each device in this embodiment can be referred to the foregoing description, and will not be repeated here.
[0143] This embodiment improves luminous efficiency by forming multiple array structures 25. By forming a conductive interconnect layer 40 on the insulating layer 30 and then removing the carbon nanotubes in the conductive interconnect layer 40, a conductive material layer 45 with a size of nanometers is formed. Compared with directly forming a nanometer-sized conductive layer, the cost of making a precision photomask is saved. The formed conductive material layer is less prone to deformation than traditional oxides. The nanometer-sized conductive material layer has better light transmittance than traditional metal patterns.
[0144] Optionally, the conductive material layer 45 includes multiple metal wires, which are arranged in any one or more ways, such as being parallel to each other, overlapping each other, or neither overlapping nor parallel.
[0145] Optionally, the conductive material layer 45 may be made of any one of gold, silver, alkali metal, or alkaline earth metal.
[0146] Optionally, the light-emitting device also includes a composite substrate 15, which includes a silicon substrate and a carbon nanotube array formed on the silicon substrate. The array structure 25 is bonded to the composite substrate 15 on the side opposite to the conductive material layer 45, that is, on the side of the first semiconductor layer 21 opposite to the active layer 22.
[0147] Optionally, the side of the array structure 25 facing away from the conductive material layer 45 is bonded to the composite substrate 15 by eutectic bonding and / or metallic bonding.
[0148] Optionally, a first adhesive layer is formed on the side of the array structure 25 away from the conductive material layer 45, that is, on the side of the first semiconductor layer 21 away from the active layer 22, and a second adhesive layer is formed on the side of the composite substrate 15 with the carbon nanotube array. The first adhesive layer and the second adhesive layer are bonded together by eutectic bonding.
[0149] Optionally, a metal electrode layer is formed on the side of the array structure 25 away from the conductive material layer 45, that is, on the side of the first semiconductor layer 21 away from the active layer 22, and a metal bonding layer is formed on the side of the composite substrate 15 with the carbon nanotube array. The metal electrode layer and the metal bonding layer are bonded by metal bonding.
[0150] Optionally, the light-emitting device also includes a buffer layer formed between the side of the array structure 25 facing away from the conductive material layer 45 and the composite substrate 15, i.e., between the first semiconductor layer 21 and the composite substrate 15.
[0151] Optionally, the wavelength of the light emitted by the light-emitting device is any one or more of the following: between 320nm and 400nm; between 280nm and 320nm; between 200nm and 280nm.
[0152] It should be understood that the application of this application is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.
Claims
1. A method for manufacturing a light-emitting device, characterized in that, include: An epitaxial structure is provided; wherein the epitaxial structure includes a substrate and a plurality of array structures disposed on the substrate; An insulating layer is covered on each of the array structures; A conductive interconnect layer is formed on the insulating layer; wherein the conductive interconnect layer includes carbon nanotubes and a conductive material filled inside the carbon nanotubes; Electrodes are fabricated on the side of each array structure that faces away from the substrate; The carbon nanotubes in the conductive interconnect layer are removed by a laser dissociation process.
2. The method for manufacturing a light-emitting device as described in claim 1, characterized in that, The formation of a conductive interconnect layer on the insulating layer includes: A substrate is provided having a conductive interconnect layer; wherein the conductive interconnect layer comprises carbon nanotubes and a conductive material filled inside the carbon nanotubes; The side of the base carrier having the conductive interconnect layer is placed above the insulating layer; Apply pressure continuously from the side of the base carrier away from the conductive interconnect layer until the conductive interconnect layer adheres to the insulating layer; then remove the base carrier. or, A dispersion containing a conductive interconnect layer is coated on the insulating layer; wherein the conductive interconnect layer comprises carbon nanotubes and a conductive material filled inside the carbon nanotubes; The dispersion is removed to form the conductive interconnect layer.
3. The method for manufacturing a light-emitting device as described in claim 1, characterized in that, Also includes: Remove the substrate; The epitaxial structure is bonded to a composite substrate on the side opposite to the conductive interconnect layer; wherein the composite substrate includes a silicon substrate and a carbon nanotube array formed on the silicon substrate.
4. The method for manufacturing a light-emitting device as described in claim 3, characterized in that, The epitaxial structure on the side opposite to the conductive interconnect layer is bonded to the composite substrate through eutectic bonding and / or metallic bonding.
5. The method for manufacturing a light-emitting device as described in claim 4, characterized in that, The step of bonding the side of the epitaxial structure away from the conductive interconnect layer to the composite substrate by eutectic bonding includes: A first adhesive layer is formed on the side of the epitaxial structure opposite to the conductive interconnect layer; A second adhesive layer is formed on the side of the composite substrate having a carbon nanotube array; The epitaxial structure is bonded to the composite substrate on the side opposite to the conductive interconnect layer through the first adhesive layer and the second adhesive layer.
6. The method for manufacturing a light-emitting device as described in claim 4, characterized in that, The epitaxial structure further includes a metal electrode layer disposed between the substrate and the array structure; the step of bonding the side of the epitaxial structure away from the conductive interconnect layer to the composite substrate by metal bonding includes: A metal bonding layer is formed on the side of the composite substrate having a carbon nanotube array; The metal electrode layer and the metal adhesive layer are bonded together by metal bonding.
7. The method for manufacturing a light-emitting device as described in any one of claims 1 to 6, characterized in that, The removal of carbon nanotubes from the conductive interconnect layer by a laser dissociation process includes: A laser with a first preset power is provided from one side of the conductive interconnect layer, the magnitude of which is sufficient to cause the carbon nanotubes in the conductive interconnect layer to be converted into carbon dioxide and overflow.
8. The method for manufacturing a light-emitting device as described in any one of claims 1 to 5, characterized in that, The removal of carbon nanotubes from the conductive interconnect layer by a laser dissociation process includes: A laser with a second preset power is provided from one side of the substrate. The magnitude of the second preset power is sufficient to peel off the substrate and, after attenuation by the array structure, cause the carbon nanotubes in the conductive interconnect layer to be converted into carbon dioxide and overflow.
9. A light-emitting device, characterized in that, include: Epitaxial structure; The epitaxial structure includes a substrate and a plurality of array structures disposed on the substrate; An insulating layer covering the plurality of array structures; A conductive material layer is covered on the insulating layer. The conductive material layer is formed by removing the carbon nanotubes, which constitute a conductive interconnect layer consisting of carbon nanotubes and conductive material filled inside the carbon nanotubes. as well as Electrodes are formed on each of the array structures.
10. The light-emitting device as described in claim 9, characterized in that, The conductive material layer includes multiple metal wires, which are arranged in any one or more ways, such as being parallel to each other, overlapping each other, or neither overlapping nor parallel.
11. The light-emitting device as described in claim 9, characterized in that, The conductive material layer is made of any one of gold, silver, alkali metals, or alkaline earth metals.
12. The light-emitting device as described in claim 9, characterized in that, The light-emitting device further includes a composite substrate, which includes a silicon substrate and a carbon nanotube array formed on the silicon substrate, wherein the side of the array structure opposite to the conductive material layer is bonded to the composite substrate.
13. The light-emitting device as described in claim 12, characterized in that, The side of the array structure facing away from the conductive material layer is bonded to the composite substrate through eutectic bonding and / or metallic bonding.
14. The light-emitting device as described in claim 13, characterized in that, A first adhesive layer is formed on the side of the array structure away from the conductive material layer, and a second adhesive layer is formed on the side of the composite substrate with the carbon nanotube array. The first adhesive layer and the second adhesive layer are bonded by eutectic bonding.
15. The light-emitting device as described in claim 13, characterized in that, A metal electrode layer is formed on the side of the array structure opposite to the conductive material layer, and a metal bonding layer is formed on the side of the composite substrate with the carbon nanotube array. The metal electrode layer and the metal bonding layer are bonded together by metal bonding.
16. The light-emitting device according to any one of claims 9 to 15, characterized in that, The wavelength of the light emitted by the light-emitting device is between 320nm and 400nm; and / or Between 280nm and 320nm; and / or Between 200nm and 280nm.